Added getScopeCacheKey in order to define the right cache key based on store ID

app/code/Magento/Catalog/Model/CategoryRepository.php

@@ -14,9 +14,11 @@
 use Magento\Framework\EntityManager\MetadataPool;
 use Magento\Framework\Exception\CouldNotSaveException;
 use Magento\Framework\Exception\NoSuchEntityException;
+use Magento\Framework\Exception\SerializationException;
 use Magento\Framework\Exception\StateException;
 use Magento\Catalog\Api\Data\CategoryInterface;
 use Magento\Store\Model\StoreManagerInterface;
+use Magento\Framework\Phrase;
 
 /**
  * Repository for categories.
@@ -144,10 +146,12 @@ public function save(CategoryInterface $category)
 
     /**
      * @inheritdoc
+     *
+     * @throws SerializationException
      */
     public function get($categoryId, $storeId = null)
     {
-        $cacheKey = $storeId ?? 'all';
+        $cacheKey = $this->getScopeCacheKey($storeId);
         if (!isset($this->instances[$categoryId][$cacheKey])) {
             /** @var Category $category */
             $category = $this->categoryFactory->create();
@@ -254,4 +258,26 @@ private function getMetadataPool()
         }
         return $this->metadataPool;
     }
+
+    /**
+     * Returns a cache key based on scope
+     *
+     * @param string|int|null $storeId
+     *
+     * @throws SerializationException
+     * @return int|string
+     */
+    private function getScopeCacheKey($storeId = null)
+    {
+        if (null !== $storeId && !is_numeric($storeId)) {
+            throw new SerializationException(
+                new Phrase(
+                    'The "%value" value\'s type is invalid. The "%type" type was expected. '
+                    . 'Verify and try again.',
+                    ['value' => $storeId, 'type' => 'int']
+                )
+            );
+        }
+        return $storeId === null ? 'all' : (int)$storeId;
+    }
 }

app/code/Magento/Catalog/Test/Unit/Model/CategoryRepositoryTest.php

@@ -168,6 +168,17 @@ public function testGetWhenCategoryDoesNotExist()
         $this->assertEquals($categoryMock, $this->model->get($categoryId));
     }
 
+    public function testGetWithStoreCodeException()
+    {
+        $categoryId = 5;
+        $categoryMock = $this->createMock(CategoryModel::class);
+        $this->expectException('\Magento\Framework\Exception\SerializationException');
+        $this->expectExceptionMessage(
+            'The "default" value\'s type is invalid. The "int" type was expected. Verify and try again.'
+        );
+        $this->assertEquals($categoryMock, $this->model->get($categoryId, 'default'));
+    }
+
     /**
      * @return array
      */

dev/tests/integration/testsuite/Magento/Catalog/Model/CategoryRepositoryTest.php

@@ -13,6 +13,7 @@
 use Magento\Catalog\Model\ResourceModel\Product\CollectionFactory;
 use Magento\Cms\Api\GetBlockByIdentifierInterface;
 use Magento\Framework\Exception\LocalizedException;
+use Magento\Framework\Exception\SerializationException;
 use Magento\Framework\ObjectManagerInterface;
 use Magento\Store\Api\StoreManagementInterface;
 use Magento\Store\Model\StoreManagerInterface;
@@ -143,6 +144,14 @@ public function testGetCategoryForProvidedStore(): void
         $fixtureStoreId = $this->storeManager->getStore('fixturestore')->getId();
         $categorySecondStore = $this->categoryRepository->get($categoryId, $fixtureStoreId);
         $this->assertSame('category-fixturestore', $categorySecondStore->getUrlKey());
+
+        $caughtException = false;
+        try {
+            $this->categoryRepository->get($categoryId, 'default');
+        } catch (SerializationException $exception) {
+            $caughtException = true;
+        }
+        $this->assertTrue($caughtException);
     }
 
     /**